1. Field of the Invention
This invention relates to a structure for mounting, on a mother board, an electronic circuit unit which has a circuit board contained in a housing. More particularly, the invention relates to a structure for mounting an electronic circuit unit enabling a wiring pattern on the circuit board to be reliably connected to a wiring pattern on the mother board without involving defective soldering.
2. Description of the Related Art
In an electronic circuit unit 50 such as the one of a television tuner as shown in FIG. 8, a circuit board 51 mounting an electronic part such as IC parts that is not shown has been contained in a box-shaped housing 52 with its both ends being opened, and these two open ends of the hosing 52 have been closed with covers 53.
FIG. 9 is a sectional view illustrating a state where the electronic circuit unit 50 is mounted on the mother board 54 along a line 9xe2x80x949 in FIG. 8.
Referring to FIG. 8, the circuit board 51 has a pair of extending portions 51a extending from one end side. Referring to FIG. 9, on each extending portion 51a is formed a terminal pattern 51d drawn from the wiring pattern 51c that is formed on one surface 51b of the circuit board 51.
The housing 52 is provided with notches that are not shown, and the extending portions 51a of the circuit board 51 are allowed to protrude beyond the housing 52 through the notches. Further, pairs of mounting legs 52a are provided on both end surfaces of the housing 52.
The thus constituted electronic circuit unit 50 is used being mounted on the mother board 54 on the set side as described below. If closely described, the mother board 54 has, formed therein, through holes 54a and 54b in which the extending portions 51a of the circuit board 51 and the mounting legs 52a of the housing 52 will be inserted. In the through holes 54a and 54b are inserted the corresponding extending portions 51a of the circuit board 51 and the mounting legs 52a of the housing 52, and the electronic circuit unit 50 is mounted on the mother board 54.
Here, the terminal pattern 51d formed on the extending portion 51a is soldered with a jet solder that is not shown onto the wiring pattern 54d formed on the back surface 54c of the mother board 54.
According to the above conventional structure for mounting the electronic circuit unit 50, however, the through holes 54a are formed in a size which includes a margin and are, hence, formed in a size slightly larger than the size of the extending portions 51a in order to prevent the terminal patterns 51d from peeling off that results when the terminal patterns 51d formed on the extending portions 51a come in contact with the inner walls of the through holes 54a at the time when the extending portions 51a are inserted in the through holes 54a of the mother board 54.
In the conventional electronic circuit unit 50, therefore, the extending portions 51a are inserted in the through holes 54a in a loose state and become rickety without accomplishing precise positioning. As shown in FIG. 9, further, a gap develops between the terminal pattern 51d on the extending portion 51a and the wiring pattern 54d on the back surface 54c of the mother board 54 giving rise to the occurrence of defective soldering.
To cope with a gap that develops between the terminal pattern 51d on the extending portion 51a and the wiring pattern 54d on the mother board 54, it has also been attempted to incorporate in the production steps a step of pushing the circuit board 51 in a manner that the terminal pattern 51d comes into contact with the wiring pattern 54d resulting, however, in an increase in the number of the steps and causing the production steps to become complex.
This invention was proposed in view of the above conventional circumstances, and provides a structure for mounting an electronic circuit unit on a mother board highly precisely and easily without causing defective soldering.
Namely, this invention provides a structure for mounting an electronic circuit unit comprising:
a circuit board provided, on one end side thereof, with extending portions having first wiring patterns formed on the surfaces thereof;
a housing for containing the circuit board while permitting the extending portions to protrude outward; and
a mother board having, formed therein, through holes in which the extending portions are to be inserted, having, formed thereon, a second wiring pattern that is to be electrically connected to the first wiring patterns, and permitting the extending portions to be inserted in the through holes so that the housing is placed thereon;
wherein the circuit board is provided with pushing means which extends separately from the extending portions on one end side, and pushes the first wiring patterns onto the second wiring pattern.
By the above constitution, according to the structure for mounting the electronic circuit unit of the invention, the first wiring pattern formed on the extending portion of the circuit board is pushed onto the second wiring pattern formed on the mother board by the pushing means, whereby the development of a gap between the first wiring pattern and the second wiring pattern is prevented. Therefore, the first wiring pattern and the second wiring pattern can be connected together without causing defective soldering, and the circuit board can be mounted onto the mother board with high precision.
Here, it is desired that the pushing means is a protruded portion extending on one end side of the circuit board, that an insertion hole in which the protruded portion is to be inserted is formed in the mother board and that by forcibly inserting the protruded portion in the insertion hole, the first wiring patterns on the extending portions are pushed onto the second wiring pattern.
With the protruded portion being forcibly inserted in the insertion hole formed in the mother board, the first wiring patterns on the extending portions are strongly pushed onto the second wiring pattern of the mother board, making it possible to reliably prevent the occurrence of a gap between the first wiring patterns and the second wiring pattern.
Here, it is desired that the circuit board is provided with at least a pair of extending portions on one end side thereof, a pair of through holes are formed in the mother board so as to be corresponded to the pair of extending portions, and the protruded portion is located midway between the pair of extending portions.
With the protruded portion being forcibly inserted in the insertion hole, therefore, the first wiring patterns on both extending portions arranged on both sides of the protruded portion can be pushed onto the second wiring pattern with a uniform pushing force.
It is further desired that the insertion hole in which the protruded portion is to be inserted is formed at a position deviated in a direction in which the first wiring patterns are pushed onto the second wiring patterns from the positions of the through holes in which the extending portions are to be inserted.
Since the protruded portion is inserted in such a manner that the first wiring patterns are strongly pushed onto the second wiring pattern, it is allowed to more reliably and strongly bring the first wiring patterns into contact with the second wiring pattern.
Here, it is further desired that the protruded portion is tapered on the surface of the side opposite to the surface of the side on where the first wiring patterns of the circuit board are pushed onto the second wiring pattern. This enables the protruded portion to be more easily inserted in the insertion hole.